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Installing a Shock-Absorbing Seat Pedestal

The versatile Shoxs helm-seat pedestal system from Allsalt Maritime softens hard landings.

How to install a pedestal seat on your boat
The Shoxs X8 is equipped with a height-adjustment feature. Tim Barker

Some say that the worst day of boating is better than the best day at the office. But that’s not true. I’ve endured too many wind-swept, slam-bang days on the water when I pined for terra firma. Such a scenario played out as we exited Miami’s Government Cut for a sea trial of the new Allsalt Shoxs helm-seat pedestal system.

Menacing 4- to 5-footers rose up and rolled in as Capt. Jordan Tilton powered through the steep seas aboard a 27-foot center-console Safe Boat. Seated in the port helm seat, I tensed and braced in anticipation of impact as we crested the face of each wave, but the pedestal softened every landing. I was riding on a cushion of air that gives this system its shock-absorbing qualities. 

Installing a Shoxs pedestal is a relatively easy DIY project, particularly if you already have a conventional seat pedestal. You can install the new pedestal on the footprint of the old one. Allsalt offers a wide range of shock-absorbing systems for commercial and military applications, but this system is designed for recreational boating and built from marine-grade aluminum with a hard-anodized silver finish. It comes in two versions, each with or without an incremental height-adjustment feature. Both include a standard square seat mounting plate with a 5 ¼-inch bolt mounting pattern, which is fairly common for most marine seats. 

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For this project, we decided to install the Shoxs X8 with the height-adjustment feature as a retrofit to the traditional pedestal on a Parker 2320 pilothouse boat. Before getting started, we removed the existing 27-inch-tall pedestal from the boat, unbolted the bucket seat (saving the hardware to reinstall the seat on the X8), and checked under the deck to ensure that no electrical wires, hoses or other components would be damaged when drilling holes.

Skill Level: 2 of 5

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Finish Time: Approx. 3 hours

Tools and Supplies

  • Allsalt Shoxs X8 height-adjust model with standard seat-mounting plate ($2,448.86; allsalt.com)
  • Power drill and 3/8-inch drill bit
  • Right-angle drill guide ($19.99; harborfreight.com)
  • 5/32-inch Allen key 
  • Socket wrench set
  • Box/open-end wrench set
  • Six 3/8-inch high-strength stainless-steel Allen bolts (length determined by combined thickness of flange, deck, and backing plate or fender washers)
  • Six 3/8-inch stainless-steel nylon locking nuts and fender washers
  • Marine sealant such as 3M 5200 ($15.99/3-ounce tube; westmarine.com)
  • Imtra 8 1/8-inch nonskid deck plate ($54.99; westmarine.com)
  • Medium-strength threadlocker such as Loctite 243
  • Marine-Tex to patch previous holes ($18.99/2-ounce jar; amazon.com)
  • Optional adapter plates as needed (allsalt.com)
Choose the proper mounting style
Mounting Style Tim Barker

The mounting flange/base comes installed in the lowest position available on the pedestal for surface-mounting. We chose this position to give us the height for this project. However, you can position the flange/base higher on the pedestal should the X8 need to recess into a deck or box for a lower seat position. This requires cutting a 6 3/4-inch-diameter hole in the mounting surface, unbolting the flange from the bottom side, sliding it up the pedestal, and retorquing it to factory specs.

Determine location of mounting holes
Mounting Holes Tim Barker

Center the supplied mounting template over the footprint of the old base and mark the position for drilling the six new mounting holes for the 10-inch-wide flange/base. Make sure the template is oriented properly, with one mounting hole positioned at the front and the other at the back of the flange, parallel with the centerline of the boat. Use a power drill and a sharp 3/8-inch bit to drill each hole. A right-angle drill guide ensures that each hole is cut perpendicular to the deck.

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Install the seat base
Install Base Tim Barker

Bed the mounting holes with a marine sealant or adhesive, and place the pedestal and flange in a position that allows easy access to the side Schrader valve’s air-fill port. Use 3/8-inch 16- or 24-thread high-strength stainless-steel Allen bolts (not supplied) of sufficient length to span the thickness of the flange, deck and backing plate or fender washers, and allow the nylon locking nuts to engage at least 0.56 inch of the bolt threads. Add threadlocker such as Loctite 243. Tighten each fastener.  

Install the pedestal seat
Install Seat Tim Barker

The Shoxs pedestal comes standard with a square adapter plate that pairs with a boat seat with a traditional 5 1/4-inch hole pattern. Remount your existing helm seat with this plate using a medium-
strength threadlocker. If you have a helm seat that does not fit the standard hole pattern, Shoxs offers additional optional seat-mounting adapters. Allsalt also offers a wide range of helm seats with optional features, such as footrests, fold-down armrests and flip-up bolsters.

Adjust the seat height
Adjust Height Tim Barker

The X8 height-adjust model lets you fine-tune the pedestal height from 25.7 to 30.1 inches tall. Use the spring-loaded knob on the side of the pedestal to retract a locking pin and telescope the seat up or down. Pull the knob and adjust to the desired height. The pedestal might not rise on its own, depending on the seat weight, so you might need to pull the seat up while the pin is disengaged. To lock the height in position, release the knob, then bounce in the seat to ensure the pin is locked.

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Adjusting air pressure of the seat
Adjusting Air Pressure Tim Barker

The Shoxs pneumatic shock-absorbing pedestal requires air pressure to function properly. There are two ports for checking and adjusting the air via a Schrader valve (same as on car tires). One is on the bottom side of the pedestal; the other is inside a small hatch just above the flange/base on the side of the pedestal. In our project, the latter is most accessible. Air pressure is preset at 85 psi at the factory. The O-ring on the pedestal shaft should be at or below the static limit indicator when the intended occupant is seated. If the O-ring is above the indicator with the occupant seated, increase the air pressure 5 to 10 psi at a time using an air compressor or hand pump with a tire-pressure gauge until the O-ring is at or below the indicator. Allsalt also offers a remote fill port in situations where both access ports are unreachable. This kit includes a section of high-pressure hose, fittings, and a fill port that can be mounted next to the pedestal or another convenient location.

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